The quasi-liquid, devices for making the quasi-liquid, and processes for making the quasi-liquid are not known in the prior art. The purpose of the preferred embodiments of the invention is to produce nanometer-scale gas bubbles or cavities that constitute the quasi-liquid. Water is the preferred fluid constituting the skin or wall of the bubble containing the gas, but other liquids are within the scope of the invention. For simplicity, water is used as the primary example herein.
While there is a scientific distinction between gas cavities and gas bubbles, this distinction has no material significance in the invention. The use of these terms herein is generally consistent with the correct distinction between the terms, but the invention encompasses an interchangeable use of the terms, such that the term ‘bubbles’ means and includes the term ‘cavities.’
While gas cavity is a gas bubble and the terms cavity and bubble are used interchangeably, an explanation of the scientific distinction may aid in understanding the background of the phenomenon employed in the invention. A gas cavity is essentially a gas within a spherical skin, or wall, that confines the gas, but the matter constituting the skin is also the matter that is outside the skin. For example, hydrogen surrounded by a water skin in a water bath would be classified as a cavity because the skin and the surrounding medium are the same matter, namely water. Because there is a different medium on only one side of the skin, the skin is said to have a single layer.
In contrast, a bubble refers to a gas within a spherical skin, or wall, that confines the gas, but the matter constituting the skin is different than the matter that surrounds the skin. For example, hydrogen surrounded by a water skin in an air environment would be classified as a bubble because the skin is different from the surrounding medium, namely air. The skin of water permits confinement of the hydrogen and a transition from the gas to the water skin to the air environment. Because there is a different medium on both sides of the skin, the skin is said to have a double layer.
An important physical distinction between a double layer bubble a single layer cavity is that there is twice the surface tension in a double layer bubble than a single layer cavity. Thus, converting from a single layer cavity to a double layer bubble immediately subjects the gas inside to twice the amount of pressure.
A disclosed device for making the quasi liquid of the invention makes micro- and nanometer-scale bubbles, typically water bubbles filled with a gas to serve as a storage medium for the gas. The aggregated bubbles are themselves a product forming a quasi-liquid.
At nanometer scales, which are generally diameters in a range of about 10 nanometers to 0.8 nanometers, surface tension can maintain the gas within a bubble at very high pressure. Importantly also, the smallness of such bubbles or cavities confers on them stability against gravitational aggregation and merging. The most common examples of high value gases usable in such a storage medium are natural gas or methane, hydrogen, and propane.
For purposes of simplifying this disclosure, hydrogen is used as the primary example of the gas because it is thought to be the best use of the invention. However, the invention is not limited to hydrogen storage or to the foregoing example gases, but may be applied to any suitable gas.
The invention is useful in creating a means for storing hydrogen in a stable medium having a volumetric energy density about the same as that of gasoline and capable of being used in a manner similar to gasoline. The preferred products from the process are useful because they are a stable suspension of nanometer-sized bubbles or cavities, which behave much as if it were a ‘liquid’ and can be burned in much the same way as gasoline or used in hydrogen fuel cells without further processing.
For bubbles that are not cavities, a preferred embodiment of the invention creates a collection of individual water bubbles of nanometer scale filled with hydrogen. When herded or aggregated together, the collection of bubbles is essentially indistinguishable from a liquid.
For bubbles that are cavities, a preferred embodiment of the invention creates a concentration or crowd of hydrogen cavities existing closely together within a surrounding water medium. This is a concentrated volume of cavities, which is preferred because the volume of the surrounding water medium is, thereby, minimized, which minimizes the size of the equipment needed and also the potential for diluting the resulting product with excess water.
The process of producing bubbles or cavities of hydrogen is generally called ‘fragmentation’ of the gas. Subsequent concentration of the cavities, or formation and capture of bubbles, is generally called ‘herding’ of cavities or bubbles.
The process of forming bubbles is termed a ‘differential condensation process.’ The process of forming cavities is termed a ‘gel process.’
Preferred methods for producing the quasi-liquid of the invention using the gel process employ any solid material having molecular-scale pores to fragment the gas to be stored into pore-sized quanta or fragments. A preferred embodiment of the invention uses a molecular-pore structure within a silica gel to fragment the gas. A typical example of silica gel is ‘aerogel’ and aerogel is used as the primary example in this disclosure. Aerogel has seen application as a desiccant to absorb water because it has a very high affinity to water. Upon contact with liquid water, it spontaneously disintegrates, which has generally been considered a negative attribute. Aerogel's high water affinity and disintegration in the presence of liquid water are useful properties for the present invention. Aerogel is also used as a thermal insulator and as a selective optical filter for infrared light. In its prior uses, aerogel has not been used heretofore for gas fragmentation, that is, to create nanometer-scale gas quanta.
Preferred methods for producing the quasi-liquid of the invention using the differential condensation process employ a channel plate having at least its exit face below the surface of liquid, typically water or a hydrophobic liquid; and an operating gas flowably connected to one end of the channel plate such that the operating gas can pass through the channel plate and out its exit face.
The preferred methods produce cavities or bubbles that are about 1,000 billion times smaller than bubbles visible to the human eye. Cavities made with the gel process are about 1,000 times smaller than the bubbles initially created after exiting a channel plate in the differential condensation process, resulting in an enhanced method for the production of nanometer gas cavities for gas storage.
While both the gel process and the differential condensation process are preferred methods of producing the quasi-liquid, an advantage of the gel process over the differential condensation process, is that the quantity of hydrogen-containing fluid flow required is greatly reduced. This is due to the factor of a thousand smaller size of silica gel pores, compared to the diameter of multi-channel plate tubes. There is also a greater simplicity inherent in the gel process. The advantage of the differential condensation process over the gel process is that the differential condensation process provides a method for constructing bubbles in a precisely controlled fashion, making it possible, for example, to obtain uniformity in bubble size. It also has the advantage of minimizing the amount of water surrounding the bubbles.
A stable product that can store hydrogen such that its energy density approaches that of gasoline has been long sought in the art. The lack of means for safe, convenient, lightweight and compact hydrogen storage is a large impediment to the widespread use of hydrogen, for example for powering automotive vehicles.
Hydrogen has the highest mass energy density of any fuel. It has about twice as much energy per kilogram as natural gas, about three times as much as gasoline and about 6 times as much as methanol. The problems stem from hydrogen's density and storage volume. At room temperature and pressure, hydrogen is a gas with a unit volume energy content about one thousand times too low for practical applications.
The liquid form of hydrogen requires a temperature below minus 253 degrees Centigrade and it has a volumetric energy density of about 8 megajoules per liter, which compares to gasoline at about 26 to 31 megajoules per liter. This temperature is impractical for most applications and even if one could maintain such temperature, the energy content per unit of volume would be still only about 25% that of gasoline.
The best pressurized-hydrogen storage systems today can achieve a pressure of about 3,600 pounds per square inch (about 250 atmospheres). Some are exploring very high-pressure storage at about 12,000 pounds per square inch (about 800 atmospheres). There is no existing art capable of storing hydrogen at about 43,500 pounds per square inch, as is the case with the present invention.
The surface tension of a hydrogen-filled nanometer-scale water bubble of the invention contains hydrogen at a pressure of 43,500 pounds per square inch (about 3,000 atmospheres). At this pressure, a suspension of nanometer-scale bubbles of hydrogen is expected to have a volumetric energy density (higher heating value) from about 24 to 29 megajoules per liter. The stated range is attributable to uncertainties in compressibility and small-scale cohesion factors. This compares favorably with the energy density for gasoline at about 26 to 31 megajoules per liter.
One of the most promising methods for storing hydrogen is intermetallic hydrides, which have up to six times the volumetric energy density of pressurized, room temperature hydrogen. However, high manufacturing costs, complex mechanisms for storing and releasing the hydrogen, toxicity problems in end-of-life disposal, and the weight penalty for such storage systems diminish their practicality. The weight penalty is notable because, for example, the best obtainable such systems require that about 93 percent of the weight be the metal storage medium and only about 7 percent be hydrogen. A discussion of the prior art for hydride alloys may be found in U.S. Pat. No. 6,193,929 to Ovshinksy on Feb. 27, 2001 entitled, “High Storage Capacity Alloys Enabling a Hydrogen-based Ecosystem.”
Conventionally, hydrogen has been stored in pressure-resistant vessels under a high pressure or stored as a cryogenic liquid, being cooled to an extremely low temperature. These methods raise safety concerns and offer less volumetric storage density than storage in metal hydrides. In addition, storage of hydrogen as a compressed gas involves large vessels and storage as a liquid involves cryogenic vessels. Such vessels make the use of hydrogen to power vehicles less feasible.
Various embodiments of the process of the present invention include a unique combination of existing technology (e.g., channel plates, lasers, sonic devices used in unrelated fields), and known fundamental processes (e.g., surface tension, density, viscosity, cooling, immiscibility of hydrophobic liquids, and water). Employing the method of the invention in these embodiments, the technologies and processes produce safe, convenient, lightweight and compact storage means for hydrogen gas.
Channel plates, also known as microchannel plates and multi channel plates, are well known, commonly available devices used in the physics community to detect photons by releasing and multiplying electrons when impacted by photons. Channel plates are essentially of a collection of micrometer sized glass tubes (also called canals, pores, or pipes) with each tube having a diameter, or pore size, from about 5 microns to about 100 microns. The formation of microchannel plates and the process of making them are well known and disclosed, for example, in U.S. Pat. No. 4,853,020 to Sink on Aug. 1, 1989. Channel plates are used in such common commercial products as scanning electron microscopes, night vision goggles and cameras.
In a preferred embodiment of the present invention, a channel plate is not used as a photon detector or electron multiplier. Rather, a channel plate serves to create micron size diameter gas flow through the pores of the channel plate. This application for channel plates is new.
In a preferred embodiment of the present invention, a hydrophobic liquid is employed. Hydrophobic liquids are well known in the art. Mineral oil, fats, waxes, liquid perfluorodecalin are all examples. Essentially, hydrophobic liquids are those that are insoluble in water.
Hydrophobic liquids have diverse uses. For example, a hydrophobic liquid can be used to coat a sweetener in a food and provide a controlled release as in U.S. Pat. No. 4,824,681 to Schobel on Apr. 25, 1989. Another example is U.S. Pat. No. 6,846,390 to Bishkin on Jan. 25, 2005 which discloses the use for hydrophobic liquid in a liquid piston pump to increase steam pressure to aid in heat transfer, and then after the energy in the steam is extracted, liquid water and hydrophobic liquid are easily separated.
When a hydrophobic liquid is combined with liquid water, the two liquids tend to separate from each other in a process called liquid/liquid partitioning. This partitioning process can in part be based on density, with one or the other rising to the top.
In a preferred embodiment of the present invention, a channel plate is used to inject the vapor of a hydrophobic liquid into a reservoir containing the liquid phase of the same substance. Micrometer-scale gas bubbles are thus formed. This is a unique application for hydrophobic liquids.
Lasers used in an alternative embodiment of the invention are also known. For example, the argon laser was invented in 1964 and is one of a family of Ion lasers that use a noble gas as the active medium. However, lasers have not been used to create nanometer-scale bubbles as in the present invention. The noted argon ion laser is highly suited to penetrate water and be absorbed only at the optical discontinuity presented by gaseous bubbles.